Safety plug and receptacle



Feb. 3, 1931. H. T. vCHANEY ET AL 791,264 v SAFETY PLUG AND RECEPTACLE Filed oct. `2e. 1925 2 sheets-sheet 1 u mllglllllgpw "Hmm Feb. 3, 1931. H. T. CHANEY ET AL v l791,254 l SAFETY PLUG AND RECEPTACLE Filed oct. 2e. 1925' amiens-sheet 2 wmv Patented Feb; a. i931 HaLLacx r. cumin, or

1 nmwamma,

PATENT' oi-Fics SOUTH HIIIZCW'AUXEIE, AND JOHN '.IAHOIPSON, 0F

wisconsin .smrr PLUG Nn nacsr'racns' lppucauon'aieaocfobeg 2s, im. semina. 64,907.

This invention relates to safety plugs and receptacles.

Objects of this invention are to provide a safety plug and receptacle for electrical trans- 5 latingl devices such as tools, irons, toasters and the like which will lessen or prevent the danger of electric shock from the translating device although defective wiring may e'xist in the device. Y y i A more specific object is the provision of a novel combination and arrangement of parts which will positively insure a permanent ground connection for the 4body of the translating device so lon as the plug-receptacle connection is rclose and in which this ground connectioncan not be impaired oi' destroyed in ordinary -usev in the hands of a novice. f Further objects are to Vprovide a plug and receptacle construction which is extremely simple, which does not detract fromv the usual appearance of these articles and which yet has the protective features discussed above. Embodiments of the invention are shown in the accompanying drawings, in which Figure'l is a sectional view of a plugand cooperating receptacle, constructed in ac cordi ance with the present invention, and showing the saine applied to anoutlet box.

Fig. 2 is a front elevation of' the device shown in Fig'. 1 .with the plug removed and the face plate broken away-for clearness.

Fig. 3 is a view similar to Fig. 1, illustrat" ing another embodiment ofthe present invention with the plug displaced from the receptacle.

Fig. 4 is a front elevation of the device shown in Fig. 3 with. the face plate broken yaway for cle'arness. l v

'This invention contemplates providin an. additional pron on the plug and an a ditional socket in t e receptacle, together with" a third wire from the additional prong, the additional prong vbeing grounded to the translating device, and `the additionalsocket being grounded to the casing or outlet box so that the translating device is ata'll times grounded while it is being supplied with cur- Botliembodiments o f the invention involve the same ty of plug.l The lug shown comprises abo y portion A w ich is equipped with a pair of prongs C, andwith an auxiliary rongC'. This auxiliary prong C is seto from the rongs'C. Each of the prongs is joined or he d to the body portion A- by means of screws B which also join tlie connectin vwires forming the cable D.

In t e embodiment of the invention shown in Fi res 3 and 4 the receptacle for cooperating with the plug A comprises a body portion F which is provided with a recessed portion F adapted to receive the body of the plug A. This receptacle is provided withv three apertures through its face, as shown in Figure 4,"and back of these apertures metal contacts or prongs R and R are'positioned, as shown in Figure 3. 'The prongs R are arranged in pairs Vand `the prong R is set ofi' tof'the side of the prongs They are each secured in place and to the connecting wires hereinafter describedl by means of the screws Q.

The receptacle F is locked to the cover plate L of an out1et`box M by means of a spring ring H. Further, it is to be noted that the rong R4 is grounded to the body of the outet box M by means of the roundwire J, suoli outlet box being-,groun ed to the conduit-N which is locked thereto by'means of the lock nuts 1 The other prongs R are connected to the service wires or leads'O. y

It is to be noted that the cover late IJ is held in place lin the usual manner y means of screws E. Thus, when the plug is in `po as sition, one ofthe prongs and consequently .one of .theJ conductors in the cable D is grounded. f

The embodiment of the invention villustrated in Figures 1 and 2 includes a receptacle 90 of a somewhat diifernt form. This vreceptacle has its insulating body carried by means of the outwardly projecting attaching lugs W which are apertured, as indicated, s o that they may be attached to the conventional outlet box.

. Itis to be noted that the stra s W are se- 7 lcured to the insulating body a by means f the screws X. This receptacle is also prov/icl.v f ed with three prongs ZandZsimilar to those we hereinabove referred to, that prongs Z lou catedin the lateral socket or aperture 2 be` v ing connected through a short conductor with one of the' screws X and from 'thence to the adjacent strap W.

The receptacle a is carried within the out` service wires, as indicated, such conduit being locked in place by means of the collar e and lock nuts, as shown.

Two `of the sockets or connectlng prongs Z are connected to the service wires, as shown,

while the third prong Z is grounded to the casing of the outlet bo'x, such outlet box being grounded by means of the metal conduit f. A face plate 7c is held in place in the usual manner by means of screws I.

It will of course be understood that two of the wires contained in the cable D are'connected with the prongs C ofthe plug A, re-

spectively and with the-active part of the.V translating device, so as to,serve as a part of the power circuit therefor, while the third wire is permanently connected to the body of the translating device and with the third prong C. Thus, when the plug is applied to the receptacle a, asin Figure l, to complete the power' circuit, the body of the translating device is automatically grounded through that third wire, prong C', contact Z', screw X, strap 11, box d and conduit f, the contact- C being automatically grounded to the outlet box upon securing the receptacle a to the box. Likewise when the plug A is applied to the receptacle F of Figure 3, the body of the translating vdevice is automatically grounded through the prong C', Contact R', lead J, outlet box M and conduit P. In both instances no external ground wire is required, the ground connections being effected through parts which are inaccessible and conse uently fool proof.

lthough the invention has been described in considerable detail, it'is to be understood that the invention may be variously embodied and is, therefore, to be limited only as claimed. We claim: v 1 5 In a separable connection of the plug and receptacle type the combination of an outlet box, a receptacle havingv prong `receiving sockets therein, current carrying contact members therein accessible through said sockets, an, additional prong receiving socket in said receptacle, an additional contact member carried by said rece tacle'accessible through said additional societ, anda support forsaid receptacle forming an'electrical `connection betweenvsaid additional contact member and said box'fto thereby effect 'a con-` nection forA said additional contact member bpon application of said receptacle to said In testimony that we claim the foregoing we have hereunto set our hands in the county of Milwaukee and State' of Wisconsm.

HALLACK T. CHANEY. JOHN M. THoMPsoN. 

